Oxygenation of arachidonic acid by hepatic microsomes of the rabbit. Mechanism of biosynthesis of two vicinal dihydroxyeicosatrienoic acids.
[1-14C] Arachidonic (eicosatetraenoic) acid was incubated at 37 degrees C for 15 min with rabbit liver microsomes fortified with NADPH (1 mM). The products were purified by high-pressure liquid chromatography (HPLC) and analyzed by gas chromatography-mass spectrometry. Based on polarity on reversed phase HPLC, the metabolites could be divided into three groups. The major metabolites of lowest polarity were 19- and 20-hydroxyarachidonic acid and 19-oxoarachidonic acid. The major metabolites of medium polarity were two diols, 14,15-dihydroxy-5,-8,11-eicosatrienoic acid and 11,12-dihydroxy-5,8,14-eicosatrienoic acid. Microsomal incubation under atmospheric isotopic oxygen led to incorporation of only one 18O molecule in each diol, indicating that the diols could originate from breakdown of 14(15)-oxido-5,8,11-eicosatrienoic acid and 11(12)-oxido-5,8,14-eicosatrienoic acid, respectively. Major metabolites in the most polar group were 14,15,19- and 14,15,20-trihydroxy-5,8,11-eicosatrienoic acid. 11,12,19- and 11,12,20-trihydroxy-5,8,14-eicosatrienoic acid and 11,12-dihydroxy-19-oxo-5,8,-14-eicosatrienonic acid. About 0.5% of exogenous radioactively labelled arachidonic was covalently bound to microsomal proteins. The metabolites and the protein-bound products were formed in considerably smaller amounts by non-fortified microsomes. Carbon monoxide inhibited this pathway of arachidonic acid metabolism, indicating that these reactions might be catalyzed by the cytochrome P-450-linked monooxygenase systems.
D015126:8,11,14-Eicosatrienoic Acid / Q000031:analogs & derivatives / Q000096:biosynthesis*; D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002851:Chromatography, High Pressure Liquid; D003903:Deuterium; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis*; D008401:Gas Chromatography-Mass Spectrometry; D008862:Microsomes, Liver / Q000378:metabolism*; D010084:Oxidation-Reduction; D011817:Rabbits
D001095:Arachidonic Acids; D002250:Carbon Radioisotopes; D005231:Fatty Acids, Unsaturated; D016718:Arachidonic Acid; C032100:14,15-dihydroxy-5,8,11-eicosatrienoic acid; C031899:11,12-dihydroxy-5,8,14-eicosatrienoic acid; D003903:Deuterium; D015126:8,11,14-Eicosatrienoic Acid